In the last article, about the service registration and discovery. In the micro-service architecture, the business will be split into a separate service, communication services and services based on the http restful. Spring cloud service calls in two ways, one is a ribbon + restTemplate, the other is feign. In this article first explains the basis ribbon + rest.
A, ribbon Profile
ribbon is a client load balancing, you can be well controlled some of the behavior of htt and tcp. Feign default integrated ribbon.
ribbon has achieved these default configuration bean:
IClientConfig ribbonClientConfig: DefaultClientConfigImpl
IRule ribbonRule: ZoneAvoidanceRule
IPing ribbonPing: NoOpPing
ServerList ribbonServerList: ConfigurationBasedServerList
ServerListFilter ribbonServerListFilter: ZonePreferenceServerListFilter
ILoadBalancer ribbonLoadBalancer: ZoneAwareLoadBalancer
Second, the preparation of
this article based on an article of the project, starting eureka-server project; project start service-hi, the port is 8762; the port configuration file service-hi changed to 8763, and started, then you will find: service-hi registered two instances eureka-server, which is equivalent to a small cluster.
Access localhost: 8761 as shown: the two clients
三、建一个服务消费者
重新新建一个spring-boot工程,取名为:service-ribbon;
在它的pom.xml继承了父pom文件,并引入了以下依赖:
<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>com.liu</groupId> <artifactId>SpringCloudLearn01</artifactId> <version>1.0-SNAPSHOT</version> </parent> <groupId>com.liu.example</groupId> <artifactId>service-ribbon</artifactId> <version>0.0.1-SNAPSHOT</version> <name>service-ribbon</name> <description>Demo project for Spring Boot</description> <properties> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-ribbon</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project>
在工程的配置文件指定服务的注册中心地址为http://localhost:8761/eureka/,程序名称为 service-ribbon,程序端口为8764。配置文件application.yml如下:
server: port: 8764 spring: application: name: service-ribbon eureka: client: service-url: defaultZone: http://localhost:8761/eureka/
在工程的启动类中,通过@EnableDiscoveryClient向服务中心注册;并且向程序的ioc注入一个bean: restTemplate;并通过@LoadBalanced注解表明这个restRemplate开启负载均衡的功能。
package com.liu.example.serviceribbon; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.client.discovery.EnableDiscoveryClient; import org.springframework.cloud.client.loadbalancer.LoadBalanced; import org.springframework.cloud.netflix.eureka.EnableEurekaClient; import org.springframework.cloud.netflix.hystrix.EnableHystrix; import org.springframework.context.annotation.Bean; import org.springframework.web.client.RestTemplate; @SpringBootApplication @EnableEurekaClient @EnableDiscoveryClient public class ServiceRibbonApplication { public static void main(String[] args) { SpringApplication.run(ServiceRibbonApplication.class, args); } @Bean @LoadBalanced RestTemplate restTemplate(){ return new RestTemplate(); } }
写一个测试类HelloService,通过之前注入ioc容器的restTemplate来消费service-hi服务的“/hi”接口,在这里我们直接用的程序名替代了具体的url地址,在ribbon中它会根据服务名来选择具体的服务实例,根据服务实例在请求的时候会用具体的url替换掉服务名,代码如下:
package com.liu.example.serviceribbon.service; import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand; import com.netflix.ribbon.proxy.annotation.Hystrix; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import org.springframework.web.client.RestTemplate; @Service public class HelloService { @Autowired RestTemplate restTemplate; public String hiService(String name) { return restTemplate.getForObject("http://service-client/hi", String.class); } }
写一个controller,在controller中用调用HelloService 的方法,代码如下:
package com.liu.example.serviceribbon.controller; import com.liu.example.serviceribbon.service.HelloService; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestParam; import org.springframework.web.bind.annotation.RestController; @RestController public class HelloController { @Autowired HelloService helloService; @GetMapping(value = "/hi") public String hi(@RequestParam String name) { return helloService.hiService( name ); } }
在浏览器上多次访问http://localhost:8764/hi?name=forezp,浏览器交替显示:
hello! 我的端口号是:8762
hello! 我的端口号是:8763
这说明当我们通过调用restTemplate.getForObject(“http://SERVICE-HI/hi?name=”+name,String.class)方法时,已经做了负载均衡,访问了不同的端口的服务实例。
四、此时的架构
一个服务注册中心,eureka server,端口为8761
service-hi工程跑了两个实例,端口分别为8762,8763,分别向服务注册中心注册
sercvice-ribbon端口为8764,向服务注册中心注册
当sercvice-ribbon通过restTemplate调用service-hi的hi接口时,因为用ribbon进行了负载均衡,会轮流的调用service-hi:8762和8763 两个端口的hi接口;
源码下载:https://github.com/MrLiu1227/MySpringCloud.git